KR100221327B1 - Asynchronous Transmission Mode Communication Scheme Scheduling Table Management Method for Real-Time Video Connection in Sublayer and Recombination of Network Interface Card - Google Patents

Abstract

According to the present invention, the maximum bandwidth means the best-effort while the effective bandwidth is guaranteed when the cell is scheduled in the partition and reassembly (SAR) sublayer of the asynchronous transmission mode communication network interface card (NIC). A sub-layer of a split and recombination (SAR) of an asynchronous transmission mode communication network interface card (NIC) in which the bandwidth is allocated to a connection for delivering a video when the bandwidth is provided, thereby improving the quality of the video service. A method of using a scheduling table for real-time video linking in a network, comprising: a connection list (1) consisting of empty entries and a connection list (2) consisting of entries allocated in the sense of "best-effort" In the scheduling table of a partition and recombination (SAR) sublayer of an AAL layer consisting of (1) is assigned first, and when the shortage of the linked list (1) is allocated in the linked list (2), the free bandwidth is characterized in that it is effectively utilized to deliver a real-time video.

Description

Asynchronous Transmission Mode Communication Scheme Scheduling Table Management Method for Real-Time Video Connection in Sub-Segmentation and Reassembly of Network Interface Cards

The present invention relates to a method for using a scheduling table for real-time video in a sub-layer of asynchronous transmission mode communication network interface card (NIC), and in particular, to a division of an asynchronous transmission mode communication network interface card (NIC). And the maximum bandwidth is guaranteed in the sense of best-effort while the effective bandwidth is guaranteed when the cell is scheduled in the recombination (SAR) sublayer. The present invention relates to a method of using a scheduling table for real-time video in a segmentation and reassembly (SAR) sublayer of an asynchronous transmission mode communication network interface (NIC) in which the bandwidth is allocated to improve the quality of a video service.

In general, the ATM Adaptation Layer (ATM) adapts the service provided by the ATM layer to the requirements of the upper layer user. Therefore, the ATM adaptation layer must provide support for the asynchronous transmission mode communication environment and the asynchronous transmission mode communication environment in addition to performing support of the user plane, the higher level control plane and the management plane.

In addition, the ATM adaptation layer maps the protocol data unit (PDU) of the upper layer to the payload section of the ATM cell, handles transmission errors, processes and flows control of lost and inserted cells. It provides timing control. The ATM adaptation layer is divided into two sublayers: a segmentation and reassembly (SAR) sublayer and a convergence sublayer (CS).

The convergence sublayer (CS) performs a function related to a specific service, and the partitioning and recombination (SAR) processes a function related to service segmentation and recombination by processing a function that is not related to service termination. Therefore, at the transmitting side, the convergent sublayer (CS) is applied as user information from an upper layer, attaches a header and a trailer, forms a convergent sublayer protocol data unit (CS-PDU), and sends it to a split and recombination (SAR) sublayer. This split and recombine (SAR) sublayer cuts it into the size of an ATM cell, attaches a header and a trailer to form a split and recombine protocol data unit (SAR-PDU) and transmits it through the ATM layer.

On the receiving side, the segmentation and recombination (SAR) sublayer extracts only the payload interval among the segmentation and recombination protocol data units (SAR-PDU) received through the ATM layer to form a convergence sublayer protocol data unit (CS-PDU). After that, the information is transferred to the convergence sublayer CS, and the convergence sublayer CS extracts only upper layer user information among the received convergence sublayer protocol data units CS-PDUs and delivers the information to the upper layer.

At this time, the header and the trailer attached to each sub-layer in the transmission process are related to error processing, buffer management, and sequence preservation. Will be passed to the layer.

On the other hand, ITU-T classifies user services into four types of A, B, C, and D according to constant bit rate (CBR), real time, and connectivity, and AAL type to correspond to these various services. It is defined by dividing into 1 to 4. In addition, the June 1992 ITU-T Conference newly discussed AAL Type 5 to support high-speed data communications.

In the AAL type 1, a real-time equal bit rate service is provided in a connected manner, and a service provided to a user is largely equal bit rate (CBR) data transfer, timing information transfer, user data structure information transfer, error recovery capability, and cannot be recovered. Display of information about errors and losses.

In general, in the partitioning and recombination (SAR) sublayer of the AAL layer, scheduling is performed by using a scheduling table. When an empty entry is reached while circulating the scheduling table, an empty cell is received. Will be sent down to the physical layer. In this case, the empty cell is a cell that does not contain any information, and when the empty cell is received in the partitioning and recombination (SAR) sublayer of the receiving AAL layer, the empty cell is discarded.

However, in the physical layer, all cells coming down from the split and recombination (SAR) sublayer are regarded as valid cells and transmitted over a physical link, thereby causing a problem of wasting bandwidth in transmitting empty cells having no information.

Accordingly, the present invention is to solve the above problems, the maximum bandwidth is best while the effective bandwidth is guaranteed when the cell is scheduled in the sub-layer of the asynchronous transmission mode communication network interface card (NIC) partitioning and recombination (SAR) sub-layer Asynchronous transmission mode communication network interface card (NIC), which is guaranteed in the meaning of best-effort, so that the bandwidth is allocated to a connection for delivering a video when there is a margin in bandwidth. It is an object of the present invention to provide a method of using a scheduling table of real-time video in a segmentation and recombination (SAR) sub-layer of.

In order to achieve the above object, the present invention provides a partitioning of an AAL layer consisting of a linked list consisting of empty entries, and a linked list composed of entries allocated in the "best-effort" sense. A scheduling table of a recombination sub-layer, characterized in that the connection list is allocated when a predetermined connection establishment request is made, and reassigned from the connection list when the connection list is insufficient.

According to the present invention configured as described above, the maximum bandwidth is best-best while ensuring effective bandwidth when scheduling a cell in a sublayer of a split and recombination (SAR) layer of an asynchronous transmission mode communication network interface card (NIC). In the sense of -effort, the bandwidth is allocated to the connection for delivering the video when bandwidth is generated, thereby improving the quality of the video service.

1 is a conceptual diagram illustrating a general ATM protocol reference model;

2A is a diagram showing a data format of an ATM cell;

2b is a diagram illustrating a header structure in a user network interface (UNI);

FIG. 2C shows the header structure at the network node interface (NNI); FIG.

3 is a diagram illustrating a data format for each layer in an asynchronous transmission mode communication method;

FIG. 4A illustrates the partitioning and recombination (SAR) sublayer protocol data unit (PDU) format in AAL type 5; FIG.

4B is a diagram illustrating a format of a common part convergence layer layer (CPCS) program data unit (PDU) in AAL type 5;

Fig. 5 is a graph showing the relationship between the cell bit rate r and time t for a given connection.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail

First, to simplify the understanding of the present invention briefly described asynchronous transmission mode communication method to which the present invention is applied

1 is a conceptual diagram illustrating an ATM protocol reference model. Here, the conceptual diagram includes a management plane, a control plane, and a user plane, and the management plane is composed of hierarchical management and plane management. In addition, the plane management means the overall management of the system, and the hierarchical management manages resource and usage variables and OAM information management.

In addition, the control plane manages call control and connection control information, and the user plane transmits user information. The protocol of the control plane and the user plane is composed of a higher layer, an ATM adaptation layer, an ATM layer, and a physical layer.

As shown in FIGS. 2A to 2C, the user's long message is divided into ATM cells and transmitted, and the received ATM cell is reassembled into one message and transmitted to the upper user. .

FIG. 2A is a diagram illustrating a data format of an ATM cell, FIG. 2B is a diagram illustrating a header structure at a user network interface (UNI), and FIG. 2C is a diagram illustrating a header structure at a network node interface (NNI).

Here, the ATM cell is divided into a header section of 5 bytes (or octets) and a user information section of 48 bytes, and the header of 5 bytes is a user network interface (UNI) as shown in FIGS. 2B and 2C. Header structure in user network interface (UNI), where the first byte is a 4-bit generic flow control (GFC) and a 4-bit virtual path identification number (VPI) identifier).

The second byte is composed of a 4-bit virtual path identification number (VPI) and a 4-bit virtual channel identifier (VCI), and the third byte is an 8-bit virtual channel identification number (VCI). The fourth byte consists of a 4-bit virtual channel identification number (VCI), a 3-bit payload type (PT), and a 1-bit cell loss priority (CLP). The byte consists of 8 bits of header error control (HEC).

Also, in the header structure of the network node interface (NNI) as shown in FIG. 2C, the general flow control (GFC) in the first byte of the user network interface (NNI) is converted into a virtual path identification number (VPI). Except for being used, it can be seen that it is identical to the header structure of NNI. This asynchronous transmission mode communication method has a hierarchical structure as shown in Table 1 below and has standardized standards for each layer.

Hierarchy Tier function Upper hierarchy Higher layer function ATM Adaptation Layer Convergence (CS) sublayer Convergence function Cutting and Recombination (SAR) Cutting function and recombination function ATM layer General flow control and cell header processing Physical layer Transmission Convergence (TC) HEC signal generation and extraction function Physical medium Bit time information function

As shown in Table 1, the asynchronous transmission mode communication method is divided into vertical structures such as a physical layer, an ATM layer, an ATM adaptation layer (AAL), and a higher protocol layer. It is divided into segmentation and reassembly sublayer (SAR) and convergence sublayer (CS) sublayer, and the physical layer is divided into physical medium (PM) and transmission convergence (TC) sublayer.

In addition, a service required by a user in an asynchronous transmission mode communication method may be classified as shown in Table 2 below according to its characteristics.

Type of service End-to-end time relationship Bit rate Connection mode Example of service Class A Real time Identity Connectivity Video signal Class B Real time variable Connectivity Variable Rate Video Signal Class C Non-real-time variable Connectivity Connectivity data Class D Non-real-time variable Connectionless Connectionless data

The AAL protocol corresponding to the service is divided into AAL 1 to AAL 5 as shown in Table 3 below.

AAL form Typical feature AAL 1 Support class A service of equal bit rate AAL 2 Support real-time, variable bit rate Class B service AAL 3/4 Support class C and D services with variable bit rate AAL 5 High speed service by simplifying AAL 3/4 function

In Table 3, the AAL layer is divided horizontally as AAL 1, AAL 2, AAL 3/4, and AAL 5 to efficiently process the corresponding service according to the type of service.

FIG. 3 is a diagram illustrating a data format for each layer in the asynchronous transmission mode communication method, in which a user service data unit (U-SDU) of a higher layer passes through an AAL service access point (AAL-SAP). After that, it is formed as AAL service data unit (AAL-SDU) and stored in AAL FIFO.In the AAL1 SAR layer, the CS-PDU is divided by 47 bytes according to the message to be transmitted by the user, and then added by adding 1 byte of SAR header. And a recombination protocol unit (SAR-PDU) is formed and sent down to the ATM layer via the ATM service access point (ATM-SAP). In the ATM layer, a 5-byte ATM header is attached to form a 53-byte ATM cell, and then transmitted to another terminal or ATM switch through an optical transmission path of the physical layer.

The AAL 5 layer is made to be suitable for high-speed data communication by reducing the overhead of the AAL 3/4 layer that transmits data of Class C and D services having variable bit rates, and the service data unit (U-SDU) from the service user. ) Transmits an ATM cell by dividing the variable length data received from the convergence layer layer CS and the convergence layer layer CS that detects a transmission error and performs identification and clock synchronization functions. It is divided into a segmentation and recombination sublayer (SAR) that recovers the CS-PDU by receiving and reassembling the ATM cell from the ATM layer.

In addition, the convergence (CS) sublayer is a common part convergence sublayer (CPCS) in charge of functions common to connectivity and connectionless services, and a service specific convergence sublayer for providing a specific AAL user service. (SSCS: service specific convergence layer).

3 is a diagram illustrating a data format for each layer in an asynchronous transmission mode communication method. Here, the user service data unit (U-SDU) of the upper layer passes through the AAL service access point (AAL-SAP) and is formed as an AAL service data unit (AAL-SDU) and stored in the AAL FIFO. In the AAL SAR layer, the CS-PDU is divided into 47 bytes according to a message to be transmitted by the user, and then a SAR header of 1 byte is added to form a segmentation and recombination protocol unit (SAR-PDU). It is sent down to the ATM layer via SAP. In the ATM layer, a 5-byte ATM header is attached to form a 53-byte ATM cell, and then transmitted to another terminal or ATM switch through an optical transmission path of the physical layer.

On the other hand, AAL 3/4 for the connection and connectionless data communication has raised the need for AAL 5 because the procedures involved in the protocol is complicated and not suitable for high-speed data communication. The AAL 5 is similar to the AAL 3/4, but has a greatly simplified function. Like the AAL 3/4, the AAL 5 is divided into a segmentation and recombination (SAR) sublayer, a common convergence sublayer (CPCS), and service-specific convergence. It has a sublayer of the sublayer SSCS.

In AAL 5, a service mode is divided into a message mode and a stream mode, and a delivery method includes a delivery guarantee method and a non-transmission guarantee method. The difference from the AAL 3/4 is that the multiplexing is not supported first, and when the multiplexing is in the AAL layer, it occurs in the service-specific convergence sublayer (SSCS).

FIG. 4A is a diagram illustrating a partitioning and recombination (SAR) sublayer protocol data unit (PDU) format in AAL type 5. FIG. Here, the AAL 5 partitioning and recombination (SAR) sublayer receives a variable length division and recombination (SAR) sublayer service data unit (SDU), which is an integer multiple of 48 octets from the common part convergence sublayer (CPCS), and receives 48 octets. A split-and-recombine (SAR) sublayer service data unit (SDU) is created.

In addition, the ATM layer provides a function of marking an end portion of a segmentation and reassembly (SAR) sublayer service data unit (SDU) so that it can be delivered without any SAR protocol overhead. In other words, any part of a segmentation and recombination (SAR) sublayer program data unit (PDU) is divided and recombined (SAR) sublayer service data unit (SDU) using the AUU (TM_User_to_ATM_User Indication) parameter of the PT interval in the ATM header. Will be included in the.

Where AUU = 1 indicates the end of the split and recombine (SAR) sublayer program data unit (PDU), and AUU = 0 indicates the beginning or middle part of the split and recombine (SAR) sublayer service data unit (SDU). .

4B is a diagram illustrating a format of a common part convergence layer layer (CPCS) program data unit (PDU) in AAL type 5. FIG. Here, the PAD section is the end of the common part convergence layer (CPCS) program data unit (PDU) payload so that the length of the common part convergence layer (CPCS) program data unit (PDU) is an integer multiple of 48 octets. Is the part that fills up to the beginning of the trailer, and the spare section fills the trailer of the Common Convergence Layer (CPCS) Program Data Unit (PDU) to be 64 bits.

The length section indicates the length of the common part convergence layer layer (CPCS) program data unit (PDU) payload section, and the CRC section shows the CRC calculation result for the common part convergence layer layer (CPCS) program data unit (PDU). It is a loading section.

Meanwhile, in the method of using a scheduling table for real-time video in the sub-layer of asynchronous transmission mode communication network interface card (NIC) according to the present invention, the remaining bandwidth which is not currently used is not used to transmit empty cells. Instead, it can be used to transmit the cell data of the video connection currently set.

In general, the video is compressed and transmitted to increase the traffic density. For connections carrying cell data of the video, the average cell rate and the maximum cell rate (typically in the asynchronous transmission mode network) In consideration of the peak cell rate, a required bandwidth, for example, an effective bandwidth is determined and allocated.

Table 4 below is a scheduling table of the partition and recombination (SAR) sublayer of the AAL layer according to the present invention.

One 2 3 One ① ① One 2 One 2 3 One ① One 2 One 3 One ① ① ① One 3 One ① ① 2 One 3 One One 2 One 3 One One One One 2 One 3 One 2 One 3 2 2 One 2 One One 2

Here, the scheduling table of Table 4 shows a case where the size is 100 as an example. The entry containing the number in Table 4 above is a valid entry (non-empty), and the entry with an empty number is an invalid entry. In addition, the entry of "1" shown in Table 4 is an entry assigned to the first connection, the entry of "2" is an entry assigned to the second connection, and the entry of "3" is an entry assigned to the third connection to be.

On the other hand, if the cell transmission rate of the link in the physical layer is ℓ, the bandwidth allocated to the first connection is And the bandwidth allocated to the second connection is And the bandwidth allocated to the third connection is to be. Therefore, the remaining bandwidth excluding the bandwidths of the first, second and third connections is to be.

Here, the method of using the scheduling table for real-time video in the segmentation and recombination (SAR) sublayer of the asynchronous transmission mode communication type network interface card (NIC) according to the present embodiment is as follows.

First, the average cell rate (1) the bandwidth allocated to the average cell rate , The maximum cell rate ( peak cell rate, or bandwidth allocated in the best-effort sense, It becomes Thus, variable bandwidth, such as : = Can be allocated when an empty entry occurs in the scheduling table. Here, FIG. 5 graphically illustrates the relationship between cell bit rate r and time t for a given connection.

On the other hand, in the embodiment according to the present invention, an AAL layer consisting of a linked list 1 composed of empty entries and a linked list 2 composed of entries allocated in the sense of "best-effort". In the scheduling table of the partition and recombination (SAR) sublayer, the connection list 1 is allocated when a predetermined connection establishment request is required, and the connection list 2 is reassigned when the connection list 1 is insufficient.

In this case, when a new predetermined connection establishment request signal is received, the average cell rate is first displayed in a connection list composed of empty entries. Cell is allocated, and then upon release of an existing predetermined connection, e.g., when the empty entry for the given connection occurs, the maximum cell ratio for the linked list in the sense of "best-perfume" to this empty entry ( The cell corresponding to) is allocated.

As such, in the process of serving using the scheduling table, unallocated entries on the scheduling table are allocated to the video connections. Then, when a new connection establishment request comes in, the cell is first assigned to an empty entry. If the bandwidth required cannot be met, then the entries that have been allocated to the video connections in the sense of "best-effert" are released. Will be allocated.

In addition, when the established connection is released, the entries allocated to the connection are reassigned to the connection that delivers the video. In other words, if a margin occurs in the bandwidth, the quality of the video service is improved by allocating to the connections for delivering the video without wasting it.

In addition, it can change and implement in various ways within the range which does not deviate from the summary of invention.

Explained above

Claims (3)

A split and recombination (SAR) sublayer of an AAL layer consisting of a linked list (1) of empty entries and a linked list (2) of entries assigned in the sense of "best-effort". In the scheduling table, Of the asynchronous transmission mode communication network interface card (NIC), characterized in that the connection list (1) is allocated upon request of a predetermined connection setting, and reassigned from the connection list (2) when the connection list (1) is insufficient. Scheduling table management method for real-time video connection in partitioning and recombination (SAR) sublayer. 2. The scheduling table of claim 1, wherein the scheduling table has an average cell rate in a connection list consisting of empty entries when a predetermined connection establishment request signal is received. Cell is allocated and then the maximum cell rate for a given connection in the sense of "best-perfume" to that empty entry upon release of an existing given connection, e.g., when a free entry for that given connection occurs. A method of managing a scheduling table for real-time video connection in a sub-layer of a network interface card (NIC) divided and recombined (NIC), characterized in that entries are allocated as many as corresponding to the number of entries. 3. The method of claim 2, wherein the varying bandwidth of the scheduling table for a given connection is determined by the average cell rate for the given connection list. ) And maximum cell rate ( A scheduling method for managing a scheduling table for real-time video connection in a sub-layer of a network interface card (NIC) partitioning and reassembly (NIC), characterized in that it is determined by the width between).